Portable drain cleaning devices are well known, being used by both professional plumbers and by the general public. Such drain cleaning devices generally include a snake, typically constituting a coiled cable, which may further be coiled inside a housing or drum from which an end of the snake protrudes from for the introduction into a pipe, sewer, drain or conduit. Often a tool is attached to the end of the snake entering the pipe or conduit, which aids in removing obstructions, for example by cutting away at the obstruction. Various tools may be interchanged with the end of the snake. The snake has the ability to rotate about its longitudinal axis as well as the ability to be axially displaced along such axis thereby creating a force used to remove obstructions in a space, for example a pipe or drain.
The ability of the snake to axially rotate and be axially displaced can be controlled by various mechanisms, and the combinations thereof, which apply a force to the snake. Often this force is applied by a motor, preferably a reversible motor, connected to a power supply. Typically the force translated from the motor to the snake, either directly or in conjunction with other mechanisms, will cause the snake to rotate about its longitudinal axis. This force may also cause the snake to elongate or retract from the drum or housing wherein it is encased when a feed mechanism is incorporated with the machine. Energization of the motor may be controlled by various devices, for example a switch. It is also typical for the direction of rotation of the motor to be controlled by a separate control device such as a lever or switch having the options of a forward, off, or reverse position. Typically the direction of rotation of the motor controls the direction of axial rotation of the drum and the snake. Additionally it is common for pneumatic switches to be used in conjunction with the motor, directed to the power supply to the motor, to further allow the operator to selectively control motor, drum, and snake rotation.
Many mechanisms have been used to increase the durability of drum augers and snakes. It is common in the art for the snake to become caught in an obstruction and become stuck. In such situations an overload of torque may be applied to various parts of the devices including but not limited to the motor, drum and snake. This can result in the deterioration and destruction of these mechanisms as well as other parts of the machine.
Torque limiting mechanisms are commonly used in conjunction with the various parts of drum augers, or other devices which include the use of a snake, to relieve strain and subsequent deterioration of various parts of the device.
U.S. Pat. No. 3,574,878 issued on Apr. 13, 1971 to Harold S. Ardley for a “Power Rooter with Safety Clutch” which teaches a spring loaded ball detent style clutch which prevents damage to a snake or burnout to the source of rotary power by slipping when a predetermined level of torque is experienced by the clutch.
U.S. Pat. No. 3,882,565 issued on May 13, 1975 to Lawrence F. Irwin and Fritz O. Ehrler for a “Spring Feed Device” where in the clutch is located within an automatic feed device. Irwin teaches that when the torque on the snake exceeds a predetermined amount of force the rate of feed of the snake slows and will stop once it has reached the predetermined amount of force. This is achieved by a spring loaded combination and chucking mechanism which engages the snake with less force as more it experiences more torque.
U.S. Pat. No. 4,364,139 issued on Dec. 21, 1982 to Larry F. Babb and Walter J. Noveske for a “Drum Type Sewer Cleaner” where a clutch can be adjusted from total slip to total lock. Babb teaches a clutch assembly being coupled to the motors drive shaft and having the ability to adjust the level of torque upon which the clutch will slip. Additionally Babb teaches the motor also having a breakdown torque.
U.S. Pat. No. 5,199,129 issued on Apr. 6, 1993 to Roy Salecker and Rockwell T. Slotter for a “Torque Monitoring System for Rotary Drain and Sewer Cleaning Apparatus” wherein a circuit measures motor drive torque levels and indicates to the operator when torque levels is above or below a predetermined torque level.
U.S. Pat. No. 5,22,270 issued on Jun. 29, 1993 to Rockwell T. Slotter and Roy Salecker for a “Electromagnetic Motor Brake Unit for Rotary Drain and Sewer Router” which teaches a brake which stops rotation of the drum. The cessation of drum rotation reduces any increased strain on the device due to the drum's possible continued rotation after power is no longer supplied to the motor. This thereby reduces the likelihood of the device tipping, opposite rotation of the drum occurring and/or breakage of the snake.
U.S. Pat. No. 6,381,798 issued on May 7, 2002 to Michael J. Rutkowski and Larry F. Babb for a “Spring Clutch for Drain Cleaning Machines” which teaches a spring arrangement which biases a drive motor on a belt driven drum-type drain cleaning machine and upon a predetermined amount of force will cause slippage between a the drive belt and drive pulley, thereby reducing torque on the snake.
The prior art addresses the problem of deterioration of the mechanisms incorporated in drum augers by mechanical means or by alerting the operator that there is an overload of torque. While such devices have improved the durability of the machine and increased safety, they do not have alternative limiting mechanisms that are directed to the direction of rotation of the drum and snake.
The prior art teaches many torque limiting mechanical devices that also deteriorate with increased use. For example a clutch that properly performs its function will typically slip after substantial use because of natural wear and tear on the parts of the clutch performing its proper function.
The prior art also teaches the ability of the torque limiting mechanisms to be adjusted to function at various levels of torque experienced by the mechanism. Although this helps in machines that have interchangeable motors, drums and snakes that can handle different levels of torque without damage to the device, it also allows for the torque level to be incorrectly adjusted and therein negate the desired effect of the mechanism. For example it is common for snakes to be interchangeable with drum augers and sewer cleaning machines. Different snakes can withstand different levels of torque without being damaged. In a situation where a snake is changed or substituted, the operator would have to adjust the clutch or torque limiting mechanism to correctly function at a torque level below that which is the maximum torque level which the snake can withstand. Where the torque limiting mechanism is not properly adjusted and set at an excessive torque level the snake may be damaged. This problem may be even more likely to occur in situations where a novice is operating the machine.
Additionally, snakes, because of their coiled spring construction, exhibit different properties depending on the direction of axial rotation and axial displacement. A snake may be rotated axially in a forward direction or a reverse direction. Rotating in the forward direction will cause the coils of the snake to compact when they encounter an obstruction. In such a situation the coiling allows the snake to withstand and exert a greater force upon an obstruction. Alternatively when a snake rotates axially, in reverse, the coiled snake will tend to unwind and definitely unwind if the snake becomes stuck in an obstruction. As a snake uncoils, reduced force on the snake should be applied or the snake will be damaged and/or possibly broken. Therefore, the likelihood of damage to the snake because of an increase in torque or another force upon the snake is greater when operated in a reverse direction than a forward direction.
The prior art shows a need for limiting torque and other rotational functionality on the various mechanisms of a drum auger by limiting the ability of the operator to control the direction of rotation of the motor, drum and snake.